only happens occasionally when free wheeling fast bumpy sections and in the middle chain ring, the chain jumps off the rings and ends up around the bb.

anyone else have this problem? am running an xt triple chainset, chain appears to be the right length, chain line is correct, was wondering if it is a single pivot issue or the shadow mech flapping around too much?

have a similar setup but XTR cranks – no jump here – I can only think chain is stretched or worn cassette or middle ring?

bike is less than 2 months old so ring and casette should be ok. replacing chain after next ride as its in the replacement zone on the chain stretch guide.

i did shorten the chain after purchase and am pretty sure its the correct length now.

Usually find this is worse on my Heckler when the rings are worn – or if I've set the chain a bit long. Take out as many links as poss.

measure chain big to big (sprockets and chain ring) and add maybe 2 links for FS. see wether the chain is too long? why did you shorten it? presumably it was OK when you bought it? or was that 2nd hand etc..

chain was too long when i bought it, it was bought new. did the big to big and the over lap was 2 whole links (one link being a wide plus a narrow link), it now overlaps one whole link. had the problem before shortening the chain which was the prompt to investigate the setup in the first place.